Given that f(x) is a continuous function and its value is positive at point x0 I need to prove that:
f(x)+1f(x)
is continuous at x0. I think this is really easy but not 100% sure. My thinking is:
1) because f(x) is continuous at x0 then limx→x0f(x) exists (definition of a continuous function at a given point).
2) Let's see if limx→x0f(x)+1f(x) exists: limx→x0f(x)+1f(x)=limx→x0(f(x))2+1f(x), provided that f(x)≠0 which is given hence the limit exists.
3) According to arithmetic of continuous functions (f(x))2+1f(x) is valid because the denominator will never be 0. Thus the (f(x))2+1f(x) is continuous at x0.
Answer
we introduce g, such as g(x)=f(x)+1f(x), which is the sum of two functions .
We know that f is continuous at x0 and non-null ( I guess), therefore, the inverse of this function is also continuous at that point.
The sum of two continuous functions at one point, is continuous, therefore g is continuous at x0
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